Ctjpola operation



l Aug. 17, v193.7.

s.v R. I Ewls ET A1. Re- 20,473y

CUPOLA OPERATION Original Filed May 3, 1955 1 2 Sheets-Sheet 1 7 7 f @5MM Inven/ors, Sidra/eg JLeae/vls,

Aug. 17, 1937. I s. R. I Ewlsr AL R- 20,473 K cuPoLA OPERATION original 'Filed nay 5,1953 2 sheets-Sheet 2 InveW//ons Sidney. R.Lew?/', Lezandfrspaln,

Byron WHageafman www ffm' Ressued Aug. 17, 1937 UNITED STATI-:s

v Re. 20,473

PATENT OFFICE CUPOLA OPERATION Sidney a. Lewis, chelsea, Leland x.

and Byron W. Hageman,

ham, Mass., assignors,

Spink. Ded- Worcester,

by direct and mesne assignments, to The Foxboro Company, Foxboro, Mass., a corporation of Massachusetts Original No.

1,977,559, dated October .16, 1934, Serial No. 669,190, May 3,

1933. Application for reissue October 12, 1936, Serial No. 105,242

1o claims.

This invention relates to the operation of cupola furnaces and the object is to provide a simple arrangement whereby a cupola may be operated under conditions involving the utilization of an accurately proportioned weight' of combustion air.

. Our invention will be well understood by reference to the following description of an illustrative embodiment thereof shown by way of ex- )'ample in the accompanying drawings, wherein Fig. 1 is a schematic view, partly in section, of a. cupola installation illustrative of our invention; and

Fig. 2 is a schematic View of the mechanism con- 5`trolling the air supply, embodying, however, to facilitate the disclosure a slight modification in the mechanical devices for actuating valve l1.

For some time best practice has ruled the use of regular and weighed proportions Aof iron, limestone and coke for each charge of the cupola. Definite procedures in starting a cupola have been followed. However, for'one reason or another air has always until recently been measured in terms of volume, the proper amount of airin terms of volume being assumed to be handled -by means of constant-speed positive-pressure blowers. Re-

cently, however, the importance of using weight of air instead of volume has been emphasized.

Fundamentally the problems arising in melting iron are problems of combustion. With this in mind, weare interested in the weight of oxygen for purposes of combustion rather than the volume of such oxygen. The apparatus which we have suggested provides the necessary corrections 35l for controlling weight rather than volume. Such corrections produce the expected saving of coal or coke due to the use of such optimum condition for combustion purposes.

Hitherto control o1' the-"weight of air supplied 40 to cupolas has been efected only by the use of a blower motor adapted to carry only a predetermined load and hence responsive to the inertia@ of the air actually displaced. Such constructions are expensive andare also not applicable to exist- 45 ing equipment. It has not hitherto been believed possible to control the weight of air through the characteristics of the flow.

.A common type of installation and one to which our invention is applicable is shown by way of ex- 50 ample in furnace 3 provided with lthe wind box 5 and tuyres 1 to which air is supplied through blast pipe 9 by means of the positive pressure type of blower Il operated by an electric motor I9. f Thefcharacter o! the flowin pipe 9 may be de- Fig. 1 wherein we have shown the cupola (Cl. 2GB-80) orifice may be determined from the following equation Px W: Kals (P. Porf where W equals mass per unit of time, K is a constant depending upon the units used in the various variables, d is the oriiicel diameter in linear measure, E is the discharge coefficient of the oriiice including the velocity of approach, P1 is the pressure on the upstream side of the oriiice, Pa is the pressure on the downstream side, and Tf is the temperature oi' the flowing air .in absolute units. The weight of air is thus a function of several variables and we herein provide a measuring instrument responsive to the several variables to produce a. resultant movement proportional to such function for governinga suitable mechanism for regulating the supply of air through the pipe 9. Herein this mechanism takes the form oi the usual spilling valve I1 on the intake side of the restriction atlli, which valve, when opened, is adapted to spill to the outer air some of the constant supply oi air under pressure delivered from the blower and thus to diminish the quantity delivered to the cupola. Herein this valve is automatically governed responsively to the weight .of air passing the restriction.l

Referring to Fig. 2, the valve I1 is -here shown as operated by a. pneumatic motor I9.' When pressure in the motor I9 increases, it lifts crosshead I9| against the force of the spring shown, swinging lever |93 upwardly (Fig. 2) about its pivot |95. This rocks bell crank |91 (Fig: 2) pivoted atx |99 clockwise. Bell crank |91 is connected. to'valve I1 by a crank |1| and the valve on thisv movement tends to close. A construction embodying a bell crank |91 is shown in patent to Johnson 542,733, July 16, 1895, the detailed construction of which may be as shown in the patent to Dixon 1,582,868, April 27, 1926. Thev controlling mechanism and the measuring mechanism which governs it may4 be organized '5 a dierential manometer.

swinging about a common center line 24 operates a control head 25 containing a valve 21 of the supply'and waste type which governs the supply through pipe 26 to the pneumatic motor I9 of operating air under pressure entering at 28, as

indicated by the arrow in Fig. 1. We refer to the' above mentioned patents for a more detailed description.

In the Dixon patent referred to the specific disclosure is of a controller inwhich the dapper 23 is moved responsively to temperature. The patent to Bristol 1,641,944, September 6, 1927, discloses a similar controller in which the fiapper is operated responsively to differential pressure set up in a flowing fluid. In accordance with our 25 invention the control mechanism may be operated to govern valve I1 responsively to the weight of huid flowing, by providing a measuring mechanism which produces a .movement proportional to the function of the several variables in the foregoing equation and which movement is utilized to position the flapper.

In Fig. 42 the mechanism illustrated for this purpose issubstantially that shown in the British (convention date), and may be considered as a differential manometer responsive to the diii'eru ential in pressure set up by the orice plate I5 and suitably compensated for the pressure of the flowing air and for its temperature. Thus, referring to Fig. 2 of the drawings, we have shown two chambers 29 and 3|I which are closed respectively by'the opposed yielding diaphragms 33 and I5. To chamber 29 is admitted through pipe 3l pressure, P1, from the upstream side of the orifice and to chamber 3l through pipe 39 pressure, P2, from the downstream side. The differential movement (P1Pz) of the two opposed diaphragms therefore measures the volume of flow through the orice', Athe mechanism forming The block interposed between and connected to the diaphragms transmits the' differential movement through arm 4i to shaft '43 to which is attached the slotted segmental crank 45 which operates ilapper 2l through connecting rod 41 which is pivotally connected to and operates arm 4l pivoted at 24,

from which arm projects a 'pin 4I for moving'4 apper 23 to the right againstthe force of its' spring (not shown), all substantially as shown o in said Dixon patent, connecting rod 45 corresponding to connecting rod I5 in that patent. To compensate for variations of lpressure and patent to`Besson et Cie 106,276, May 2, 1916 vary. The block 56 between these two die phragms 49 and 5l is traversed by a rocker arm 51 on a shaft 59. 'I'he aggregate motion of the diaphragms is therefore transmitted to the shaft which carries an arm 6| the other end of which is supported by the adjustably tensioned spring BI, as described in the Besson British patent referred to. Ann 6| is connected by a link 85 (herein shown adjustable as to length by means of a turnbuckle 66) to the connecting rod 41, the link being pivoted at its ends to the arm and rod.

It will be clear from the drawings that if the pressure P1 increases, tending to rock arm 6| counterclockwise about shaft 59, this motion will be transmitted through link and the point of connection of connecting rod 41 will be slid outwardly along crank 45 and the flapper 23 will be operated responsively to the product of the differential pressure and the static `pressure. In other words, arm 46 and therefore iiapper 23 are moved as is arm p in the aforesaid British patent to Besson, but this motion is used primarily to effect a control operation rather than an indicating or recording operation.

5I and tending to rock arm 6I clockwise, the point be proportional to the quotient of the differential and the temperature. The aggregate movement transmitted to the flapper is thus proportional to P1-Pana Tf and while it might be transformed into the square Vroot of that expression the form given is equally available for control purposes.

In actual practice we prefer to utilize a differential `manometer provided with means for temperature and pressure compensation devised by w. w. Frymoyer, of Foxboro, Massachusetts. for which. we understand he has filed application for Letters Patent lof the United States, Serial No. 666,132, filed April 14, 1933. We herein dis# close the mechanism illustrated in Fig.2 to emphasize the fact that our invention is independent of thev particular measuring instrumentality employed. l

We are aware that the invention may be em` bodied in other specific forms without departing from the spirit or essential attributes thereof, and we therefore desire the present embodiment to be considered in-all respects as illustrative' and not restrictive; reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention We claim:

1. The combination with a cupola and its blast pipe 'of a. blower of the positive pressure type supplying air tn the pipe, means in the blast pipe temperature, the connecting rod 41 may be gud d0 Produce a differential pressure, a valve at the along the crank 45 so that as the pressure Pi 5 increases, the apper 23 will be operated through a crank arm of increased length, and as the temperature increases, the length of the' crankarml will be shortened. Herein the pressure Px admitted to chamber 29 acts also on a diaphragm 'mllwhich is opposed by a diaphragm Il; The

space in the rear 'of diaphragm 5i is connected through 'a passage 53 with a thermometer bulb i5 in blast pipe 9. This bulb may contain volatile fluid so that as the temperature varies, the vapor 'I6-pressure acting ori-diaphragm Il will likewise compressor side of said means for spilling air from the blower, differential pressure l m means with means for temperature and pressure tion attached thereto, control means actuated by the diiferential measuring mechanism to operate said valve so that a'constant weight 'of air is-advanced'throllh Said blast pipe t0 the cupola per unit of time.

.2. The combination of Va positive pressure bl0w.4

er means. for-"melting metals of the type and the combustible material are lntimatelyassoelatem a blast .pipe conductingl Similarly, if the temperature increases, pressing on diaphragm in the blast pipe to produce a diiierential pressure when air is iiowing, means for measuring temperature and pressure within the blast pipe attached thereto, control mechanism actuated by the combined reactionsof `the diiilerential measuring means and the pressure and temperature compensation, and valve means actuated by said control mechanism to spill excess air to atmosphere, said spilling means being so actuated that air through blast pipe is maintained at a. constant weight rate.

, 3. The combination with a cupola and its blast pipe of a positive pressure blower supplying air in excess o! a constant weight rate to the atmosphere. means for measuring the ilow of air through the blast pipe compensated for temperature and pressure, and control means actuated by measuring means to operate the valve.

4. The combination with a furnace for melting metals of the type where metal and combustiblematerial areintimately associated, a blast pipe for conveying air under pressure thereto. a valve controlling the supply oi!V air passing through the pipe, means in the pipe for creating a differential pressure in the iiowing air, means for measuring the diil'erenti'al, means tor compensating said measuring means for pressure and temperature of 'the air, and controlling mechanism actuatedby the combined reactions oi! the difierentlal measuring means and the pressure and temperaturecompensating means governing said valve.

5. 'Ihe combination with a furnace for melting metals of the type where metal and combustible' material are intimateLv associated, a. blast pipe for conveying air under pressure thereto, means 40 for regulating the supply o! air passing said pipe.

means in the pipe for creating a differential pressure in the owing air, means for measuring the diilerential, means i'or compensating said measuring means for pressure and temperature o! the air, and controlling mechanism actuated by the combined reactions of the differential measuring means and the pressure and temperature compensating means governing said regulating means. 6. 'I'he combination with a furnace for melting metals of the type where metal and combustible material are intimately associated, a blast pipe for conveying air under pressure thereto, means in the pipe for creating a differential pressure in thel flowing air, a valve interposed between said means and the compressor for diverting some of the discharge of the compressor from the pipe, means for measuring the differential, means for compensating said measuring means for pressure 00 and temperature of the air, and valve actuating means governedv by the combined `reactions oi' said di'erential pressure-measln'ing lmeans and the pressure and temperature-regulating means.

air from the blower to the melting means, means the diierential. means for compensating for thev to the pipe, a valve in the pipe for spilling air.

7. In combination with apparatus requiring a supply of gas at a predetermined weight for efilcient operation, a conduit for conveying gas thereto. meansA for regulating the ow of gas through the conduit, other means for measuring the volume of the gas owing through said conduit, means for compensating said measuringy means for the pressure and temperatureV of the gas, and control mechanism actuated by the combined reactions of the flow measuring means and the pressure` and temperature compensating means governing said'regulating means.

8. In combination with apparatus requiring a supply of gas at a predetermined weight for efcient operation, a conduit for conveying gas thereto, and apparatus for controlling the weight of gas ilowing through said conduit comprising means for measuring the volume of gas iiowing throughk the conduit, means for compensating said measuring means for the temperature and pressure of the gas. control mechanism actuated by the combined reactions of the ilow measuring I neans and the pressure and temperature compensating means, and valve means actuated by said control mechanism, said last Vnamed means being so actuated that the weight of gas owing through said conduit is maintained at a prey determined value.

9, In combination-with apparatus requiring a supply oi' gas at a predetermined weight for efcient operation, a conduit for conveying gas thereto, means for regulating the flow of gasV through the conduit, other means for measuring the volume of the gas flowing through said conduit, means for compensating said measuring means for the pressure and temperature oi.' the gas, control mechanism including a pneumatic i control couple for governing said regulating means, and means for controlling the relative motion o f the elements of said control couple responsive to the combined movements of the ilow measuring means and the pressure and tem-` perature compensating means.

10. In combination with apparatus requiring a supply of gas at a predetermined weight for ef'- cient operation, a conduit for conveying gas thereto, means for regulating. the flow of gas through the conduit, other means in said conduit for creating a dlderential pressure in the means, and means for controlling the relative motion of the elements of said control couple responsive to the combined movements of said rst, second and third movable means. p

, SIDNEYER. LEWIS.

mmm) K. sfuma.` BYRON W. HAGERMAN. 

